EP1420983A2

EP1420983A2 - Method for triggering at least one airbag in a vehicle

Info

Publication number: EP1420983A2
Application number: EP02701180A
Authority: EP
Inventors: Stephan BENTELE-CALVÖR; Klaus Oswald; Torsten Grotendiek; Klaus Mindner; Gerhard Loeckle; Barbara Gatzweiler
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2001-02-24
Filing date: 2002-01-10
Publication date: 2004-05-26
Anticipated expiration: 2022-01-10
Also published as: WO2002068246A3; DE50206329D1; JP4015552B2; US20030160436A1; JP2004523415A; EP1420983B1; US7036845B2; WO2002068246A2; DE10109043C1

Abstract

The invention relates to a method for triggering at least one airbag in a vehicle, whereby at least two criteria are used to decide to ignite the second stage of a two-stage airbag. To this end, variables derived from measuring signals of an acceleration sensor are used as criteria. Said variables must exceed threshold values within pre-determined periods of time in order to trigger an ignition decision. The criteria are selected according to the type of vehicle. Characteristic curves are used as threshold values. Said characteristic curves can optionally be modified according to the change in a seat belt.

Description

Method for deploying at least one airbag in one

vehicle

/

State of the art

The invention is based on a method for triggering at least one airbag in a vehicle according to the preamble of the independent claim.

It is already known to use two-stage airbags, even continuously switchable airbags being possible.

Advantages of the invention

The method according to the invention for triggering at least one airbag in a vehicle with the features of the independent claim has the advantage that at least two criteria must be met in order to ignite the second stage of the airbag prematurely. Different ones of the at least two criteria are possible, for example an AND link which brings greater certainty that it is really a triggering situation, or an OR link which allows greater certainty that a triggering situation is highly likely is recognized. This makes the detection of an impact with a large accident severity safer and thus also the use of the corresponding multi-stage airbag. In particular, it can be checked that the two criteria must be met in good time. In the event of an impact with a low accident severity, a criterion can then be used as an exclusion criterion. It is thus possible for the second stage of the two-stage airbag to be triggered after a predetermined maximum time, in order to mitigate the effect of the two-stage airbag. The measure of force per time becomes smaller. In addition, it should be noted that if the second stage is ignited after a longer period of time, the gas already reflows, so that the second stage is therefore also mitigated. Overall, a sharper separation between one-stage and two-stage deployments from an airbag in the event of an accident is possible using the method according to the invention.

The measures and further developments listed in the dependent claims permit advantageous improvements to the method for triggering at least one airbag in a vehicle, as specified in the independent patent claim.

It is particularly advantageous that the criteria for activating the at least two-stage airbag are selected as a function of the vehicle type. In this way, the respectively suitable criteria for the respective vehicle type are selected, so that an optimal use of the at least one airbag is possible.

Furthermore, it is advantageous that, as the suitable parameters that form the criteria, the variables derived from the acceleration sensor, such as acceleration in and transverse or at an angle to the direction of travel, the corresponding integrated accelerations, double integrals of the accelerations and combinations of such accelerations in and be selected transversely or at an angle to the direction of travel, the suitable parameters for forming the criteria being selected by means of crash tests, empirical data and simulations.

It is also advantageous that the second stage of the airbag is always fired after a predetermined remaining ignition time when the airbag is used, so that the effect of a two-stage airbag is thus mitigated.

In addition, it is advantageous that a minimum delay time between the firing of the first and the second stage must be observed, which avoids destruction of the squib. This minimum delay time is also determined by how the trim parts of the airbags are likely to fly through the passenger compartment.

Furthermore, it is advantageous that the threshold values are designed as characteristic curves, so that appropriate crash courses can then also be dealt with by the suitable choice of the characteristic curves. It is thus possible for the threshold values to adapt to an accident over the course of the accident.

It is particularly advantageous that the criteria have to exceed a respective threshold value for a predeterminable decision time in order to recognize that the respective threshold value has been exceeded. This means that short peaks that exceed a threshold are not used as a trigger decision. This makes the method according to the invention safer in terms of triggering restraint devices. If both criteria that are used to ignite the second stage of the airbag are above their respective threshold values within a predefinable accident severity time, then a serious accident is recognized and the ignition of the second stage is carried out after the minimum delay time in order to provide maximum protection for the occupants.

It is also advantageous that the use of a belt has an influence on the characteristic curves, so that the airbag is triggered accordingly depending on this. This takes into account the interplay of the belt and airbag in personal protection. If there is no use of a belt, then airbags must be fired accordingly at lower accelerations, since then the entire restraining force must be provided by the airbag. In such a case, the corresponding threshold value must therefore be lowered, so that a trigger signal is already generated with one parameter than with the use of a belt.

Finally, it is also advantageous that there is a device for carrying out the method according to the invention, which has acceleration sensors, a processor, memory and connections to restraint means in order to be able to carry out the method according to the invention. In one development, it can be provided that acceleration sensors are arranged separately from the airbag control unit in the vehicle, for example as upfront sensors, that is to say those sensors which are arranged in the front of the vehicle, that is to say as close as possible to a front impact.

drawings

Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. 1 shows a block diagram of the device according to the invention, FIG. 2 shows a block diagram of the method according to the invention, FIG. 3 shows the triggering scenarios, FIG. 4 shows a first speed-time diagram of the X integrator curve, FIG. 5 shows a second speed 6 shows a third speed-time diagram of the X-integrator curve, FIG. 7 shows a fourth speed-time diagram of the X-integrator curve, FIG. 8 shows a fifth speed-time diagram of the X-integrator curve and FIG. 9 shows a sixth speed-time diagram of the X integrator curve.

description

A multi-stage airbag, in particular a two-stage airbag, is to be ignited according to the severity of the accident. According to the invention, two criteria are used here to be linked to one another. In the exemplary embodiment, the criteria are weighted equally. A logical AND link is to be used to make a decision as to whether and when the second airbag stage should be triggered. It is also possible that three or more criteria are used and / or other combinations of the criteria are used. An OR, a NAND and other logical links pay for such links. However, a static link is possible, for example a correlation.

FIG. 1 shows the device according to the invention for carrying out the method according to the invention for triggering at least one airbag in a vehicle as a block diagram. An airbag control device 9 has an acceleration sensor 1 in the direction of travel, that is to say the X direction, and an acceleration sensor 2 transversely to the direction of travel, that is to say in the Y direction, or both are installed at an angle to the direction of travel. Furthermore, the control device 9 has the signal processing 3 and 4, a processor 5 and a memory 6. The X-fogging sensor 1 is connected to an input of the signal processing 3. The signal Processing 3 is connected to a first data input of processor 5.

The Y acceleration sensor 2 is connected to an input of the signal processing 4. The signal processing 4 is connected to a second data input of the processor 5. The processor 5 is connected to a memory 6 via a first data input / output. The processor 5 is connected to a control 7 for restraint means via a second data input / output. The control 7 is connected via its second data input / output to restraint means 8, here a two-stage airbag.

Acceleration sensors 1 and 2, which are designed here as micromechanical sensors, deliver output signals in accordance with the vehicle accelerations determined, which are filtered and amplified by electronics located on sensors 1 and 2, in order to then transmit the signals to signal processing units 3 and 4, respectively , The signal processing 3 and 4 each have an analog-digital converter and prepare the digitized measurement data for the processor 5. If necessary, a data telegram transmission is carried out here, which is then received by the processor 5. Alternatively, it is possible that the signal processing 3 and 4 are each assigned to the sensors 1 and 2 or the processor 5. It is still possible to use peripheral acceleration sensors. The signals of the peripheral acceleration sensors are then transmitted to the control unit 9 via two-wire or bus lines, data telegrams then being used. Appropriate interface modules must then be provided.

The processor 5 evaluates the acceleration signals from the acceleration sensor 1 and the acceleration sensor 2 by, on the one hand, the pure acceleration signals and also processes accumulated acceleration signals as well as double integrated acceleration signals. A criterion is used for the first airbag stage as to whether or not deployment should take place. Independently of this, two further criteria are used for the second stage, which are determined by an AND link when the second stage is triggered. Ultimately, there are three criteria that are checked to ignite the second stage, the criterion for the first stage being calculated independently of the review of the two further criteria. The x acceleration signal, ie in the direction of travel, is used here as the criterion for the first stage. The second stage only triggers if the first stage has already triggered.

Two signals are used as the criteria for the second stage, wherein one signal can also be used for both criteria. If, for example, the X integrator, ie the integrated acceleration signal in the x direction, is used as a criterion in the method according to the invention, it is possible to use the X integrator as a second criterion. Since the threshold values are designed here as characteristic curves, which therefore change as a function of time, when the X integrator is used, different characteristic curves and thus different threshold values are used for both criteria for the second stage. It is crucial that both criteria are derived from the signals of the acceleration sensors 1 and / or 2, with derivative also being understood to mean the direct use of the acceleration signals.

The threshold values that are used for triggering decisions are stored in the memory 6, in which times and intermediate results are also stored. The times determine when an event occurred. For example, there is a trigger decision or not.

The control unit 9 communicates with the control 7 in order to receive diagnostic data from the restraint means 8, so that it can be determined whether the restraint means 8 are ready for operation. This applies in particular to the functionality of ignition devices, that is, squibs that are monitored by resistance measurements. Trigger commands are also transmitted from the processor 5 to the control 7, so that the restraint means 8, that is to say the two-stage airbag, can then be triggered. To do this, the squib is ignited with an ignition current.

FIG. 2 shows the method according to the invention as a block diagram. In block 10 Acc, the criteria derived from acceleration sensors are determined and passed on to further evaluation blocks 11, 12 and 13. In block 11, criterion A, for example the X acceleration signal, is evaluated. In block 12B, the second criterion, for example the summed up X acceleration signal, is evaluated. In block 13 it is decided on the basis of the X acceleration signal whether the first stage of the airbag is to be deployed, that is to say whether the restraining means have to be used at all. This is also determined by a threshold value comparison. The basic algorithm therefore runs here. In block 14, a logical AND combination of criteria A and B is carried out and a check is made as to whether the first airbag stage has been triggered. If criteria A and B are met within a certain time and the first stage is ignited, then the second stage, second stage, is also ignited in block 15. Ultimately, three criteria for the second stage were checked. It is therefore crucial that two criteria have to be met in order to ignite the second stage within a predetermined time after the first stage. Both criteria are derived from the acceleration signals. Regardless of the fulfillment of the criteria, the 2nd stage triggers when the 1st stage has triggered. The decisive factor is the chronological sequence of triggering the 2nd-stage after the first stage.

In Figure 3 three different trigger scenarios are shown. In triggering scenario A, it has been found that the first stage has triggered within an accident severity time stored in the memory 6. Therefore, the second stage of the airbag is triggered after a minimal delay time tüeiay _Fas . In such a case, since there is a serious accident, the high acceleration signal triggers the first airbag stage. It is therefore necessary in such a case that the airbag ignites the second stage with minimal delay in order to ensure optimum protection of the respective occupant. In this case, no waiting for the criteria to be met.

The use of the airbag can of course also be seen depending on the individual. Occupant classification systems ensure that the airbag is not itself the cause of injuries to vehicle occupants. For example, an airbag is not used in children if head injuries are to be expected.

Scenario B indicates that after igniting the first stage, the second stage can be ignited after a time window from t _delay to tüeiayMa _x . This is of particular interest in the case of moderate accidents. In the case of minor accidents, scenario C is used, then the second stage after the maximum paint time, the residual ignition time t ^ elaydisposal ignited so that the effect of the two-stage airbag is minimal.

The following shows speed-time diagrams, i.e. the X integrator. For the sake of simplicity, only one criterion for the second stage is shown, it being assumed that the first stage was triggered by evaluating a separate criterion and that the second criterion for the second stage behaves like the first criterion for the second stage.

FIG. 4 shows scenario A in a first speed-time diagram, with integration time 16 being displayed on the time axis: the X-integrator of the basic algorithm exceeds the triggering threshold within T _almost , the first airbag stage being triggered. The second airbag stage is thus triggered after the corresponding delay time T _e i _a yfast.

FIG. 4 therefore shows the X integrator signal 18 as a function of the time 16. The curve 19 describes this signal. Here is the case that the second stage Second Stage is _ignited after a minimum time t _cje] _ _a yf _as - | - after the ignition of the first stage First Stage. This depends on the fact that within the time tf _ast the first stage has tripped. So there is a serious accident here, as high accelerations occurred in a very short time.

FIG. 5 shows a second speed-time diagram, which illustrates how a criterion, for example the absolute X integrator for the second stage, is satisfied after the first stage has been ignited. The abscissa 16 describes the integration time, while the ordinate 20 indicates the speed, that is to say the integrated acceleration signal. If threshold 22, a noise threshold from the inte- Grator of the basic algorithm exceeded, then the threshold 23, which is designed here as a characteristic, is started. At time 24, the first stage is fired by the basic algorithm. After this ignition, a break from tςjelay must be observed to avoid destroying the squib. At time 40, criterion 21 exceeds threshold value 23. That is, the criterion is fulfilled from now on. However, since it is stipulated that this criterion lasts at least for the time being are met, that is, the signal 21 is above the threshold value 23, it is only at time 25 that the criterion is finally met. At this point in time 25, the second stage of the airbag is then ignited if the further criterion, not shown, which is treated in accordance with the illustrated criterion, has also been met by this point in time. Up to the time i-delay max i ^{it is} possible to ignite the second stage in this way. If the curve 21 were above the threshold 23 only after the time ^ delay max ^ ^ur the time t _ro j- _lus - | -, then the second stage is ignited only with the remaining ignition time t ^ elay (see in FIG. 8, Time ^¬ point 32).

A third speed-time diagram is shown in FIG. The abscissa, ordinate and the threshold value 22 and the threshold value 23 are as in FIG. 5. Here, the case is shown that a criterion for the second stage is met before the first stage has been ignited. Then the second stage is ignited after the minimum time ^ elay. The prerequisite is that the further criterion is also available early. Criterion 26 exceeds the threshold value 23 at time 41. The threshold value is above this threshold value 23 for the time t _ro k _us -ι-. Therefore, at time 27 after the time t _roj -, _us -ι- has expired, the processor 5 recognized and stored that the Criterion is also met. This is then set in memory 4 as a trigger flag. The first stage of the airbag is now triggered at time 42. At time 43, the time tζjelay ^c ^ ^em i ⁿ i ^ma l time after which the second stage may be ignited has expired and now the second stage, second stage, is also ignited.

A fourth speed-time diagram is shown in FIG. The abscissa and ordinate as well as the threshold 22 and the threshold 23 are as before. A criterion 28 now describes the measured signal. At time 44, measurement signal 28 exceeds threshold 23 for the first time. At time 29, the time t _ro] - _{) US} - ₍ - has expired, so that it is then recognized that the criterion has been met. At time 30, the first stage is now ignited and after the time tdelay at time 31, the second stage And this, although the curve 28 is now below the threshold value 23. The prerequisite is that the further criterion is met by the point in time 31.

FIG. 8 shows a fifth speed-time diagram, in which the ordinate and abscissa, threshold value 22 and threshold value 23 are used as before. Curve 37 describes the criterion. At time 33, the first stage of the airbag is deployed. Starting from time 33, the time t ^ elay is waited, in which no second stage may be fired. At time 45, measurement signal 37 exceeds threshold value 23. Starting from time 45, time t _ro k _ust starts within which, however, measurement signal 37 drops below threshold value 23, so that when time t _ro k _us - | - at the time 46 it is determined that the criterion has not been met. Therefore must now, so wait until the expiry of the residual firing time td _e ι _a y Dispo _sa l up to the time 32 in order to ignite the second stage. The remaining ignition time t ^ eia _y disposal ϊ- ^s ^ the time at which the second stage is ignited at the latest. This is irrespective of whether the further criterion is met or not. Since criterion 37 is not fulfilled, the second stage always triggers at time 32.

5

FIG. 9 shows a sixth speed-time diagram, in which the abscissa and ordinate as well as the threshold values 22 and 23 are the same as before. The curve 34 describes a criterion. At time 35 the

.0 first stage ignited. However, since curve 34 does not apply to any

Time exceeds the threshold value 23, the second stage is only ignited at time 36 after the end of the maximum delay time, the residual ignition time t ^ elay dis _p osal. This is irrespective of whether the further criterion is met

.5 is or not. Since criterion 34 is not fulfilled, the second stage always triggers at time 36.

Two criteria are used to trigger the second airbag stage. These criteria are separated

: 0 calculated by the basic algorithm. Only the first airbag stage is triggered via the basic algorithm. The decision to deploy the second airbag stage depends on two criteria for medium and low crash severity. There are also more possible. The criteria can be from one

15 criteria pool can be freely selected and combined. The X integrator of the acceleration signal can be used as criteria. However, it is possible to use other parameters here. This includes the Y integrator, a combination of the X and Y integrators or a double integral of the

0 Y integrators. The first criterion used for the basic triggering algorithm for triggering the restraint means can also be the X integrator. With the integration it is possible that this is only viewed in a window or that this is only determined by the amount

5 speed signal is taken or that this is from the NEN speed signal, i.e. classic, is used. This also applies if the sensors are attached at an angle to the direction of travel, for example. If the crash severity is high, ie if the first airbag stage triggers within the crash severity time Tfast, the second airbag stage is triggered after Tdfast, regardless of whether the criteria for the second stage have already been met.

Claims

Expectations

1. A method for triggering at least one airbag (8) in a vehicle, the at least one airbag (8) being used with at least two stages, an airbag control unit (9) centrally arranged in the vehicle having at least one acceleration sensor (1, 2 ) used to record the vehicle acceleration, characterized in that the second stage of the at least one airbag (8) is triggered as a function of a linkage of at least two criteria derived from the at least one acceleration sensor (1, 2).

2. The method according to claim 1, characterized in that the second stage is triggered if the at least two criteria are each above predetermined threshold values within respective predetermined times.

3. The method according to claim 1 or 2, characterized in that the criteria are selected depending on the vehicle type.

4. The method according to claim 1, 2 or 3, characterized in that the criteria are selected from the following parameters: acceleration in the direction of travel, summed acceleration in the direction of travel, summed amount of acceleration in the direction of travel, summed loading acceleration in the direction of travel in a given time window, acceleration across the direction of travel, total acceleration across the direction of travel, sum of the total acceleration in and across the direction of travel, double integrated acceleration across

Direction of travel, acceleration determined at an angle to the direction of travel.

5. The method according to any one of claims 2 to 4, characterized in that if at least one criterion does not reach the respective threshold value (23) in the respective time, then the second stage is ignited after a residual ignition time (tdelay disposal).

.5 6. The method according to any one of claims 1 to 5, characterized in that a minimum delay time (elay) is specified for ignition of the second stage.

7. The method according to any one of the preceding claims, characterized in that a time-dependent characteristic curve (23) is used as the threshold values.

8. The method according to any one of the preceding claims, characterized in that when a respective criteria

! 5 µm is above the respective threshold value (23) for a predetermined decision time (t _ro bust), upon detection of the respective threshold value (23) being exceeded by the respective criterion.

SO

9. The method according to claim 6, 7 or 8, characterized in that the second stage is ignited after the minimum delay time (tdelayfast), provided that the first stage triggers within a predetermined accident severity time (tfagt).

! 5

10. The method according to any one of the preceding claims, characterized in that the characteristics are changed depending on the use of a belt.

11. Device for performing the method according to one of claims 1 to 9, characterized in that the device has at least one acceleration sensor (1, 2) for impact detection, a processor (5), a memory (6) and at least one airbag (8) , which can be switched in at least two stages.

12. The device according to claim 11, characterized in that the processor (5), the memory (6) and the at least one acceleration sensor (1, 2) are housed in an airbag control unit (9).

13. The apparatus according to claim 12, characterized in that the airbag control unit (9) can be connected to outsourced acceleration sensors.